Double skin facade model

Hi all, I’m working on a LEED certification on an office building with a double skin facade. According to the proposed design recommendations, the double skin has to be modelled with a special thermal zone dedicated. Whereas in the baseline model recommendation the double skin shall not be modelled. This different way to model the building make the building area different and the building zoning different. The problem is that in the design model part and the thermal block part of the ASHRAE 90.1 - 2007 Appendix G , it is said that this is not allowed. In the design model section, it is said that the baseline model shall have “the same number of floors and identical conditioned floor area” and in the thermal block section it is said that the baseline model should be the same as proposed design. One solution should be not to model the double skin facade in both models, but it seems not really accurate to model the building like that compare to the real building. So my question is, how to model a double skin in the proposed design while respecting the same thermal zoning and the same building area as the baseline design ? (My guess is to model the double skin facade in the proposed design with an appropriate thermal zone in designbuilder, not to model the double skin in the baseline case and taking as baseline exterior wall boundaries the interior wall of the double skin in the proposed design. However, the thermal zoning will not be the same) Thank you for your answer, Best regards,